The invention relates generally to the field of orthodontics in which malaligned teeth receive corrective braces to reposition the teeth into proper alignment in the dental arch. More specifically, an orthodontic bracket is provided in which horizontal and vertical sight lines are used to facilitate alignment when the bracket is mounted on a tooth. The invention also is directed to an archwire recess that both facilitates alignment and reduces frictional forces between the archwire and the archwire slot.
As is well known in the art, malaligned teeth can be corrected by moving them into their proper orientation using orthodontic brackets. With the development of better adhesives to bond orthodontic brackets to a tooth, the size of the orthodontic brackets have become smaller and smaller over the past number of years. As a consequence, and because present day adhesives have a tendency to dry rapidly, the amount of time an orthodontist has to place an orthodontic bracket on a patient's tooth, before the adhesive drys, is reduced to a matter of seconds. Coupled with the small size of the orthodontic bracket itself, orthodontists have routinely sought new bracket designs to facilitate alignment of orthodontic brackets on the tooth.
More specifically, orthodontists have sought bracket designs and methods which help align the archwire slot with the occlusal plane of the patient's teeth. A further reference line, although imaginary, is the tooth long axis of the tooth. Thus, the occlusal plane and the tooth long axis are two reference lines which the orthodontist utilizes in mounting a bracket on the tooth.
Some prior art brackets, such as that shown in U.S. Pat. Nos. 3,477,128; 3,660,900; and 3,881,252, depict various orthodontic brackets in which the archwire slot is slanted with respect to the tie wings. By slanting the archwire slot, each orthodontic bracket can be mounted such that the archwire slot of each bracket on each tooth is parallel to the occlusal plane which insures that all of the archwire slots of the various orthodontic brackets will align parallel to the occlusal plane. When the archwire is then fitted into the archwire slot of each bracket, the archwire also will be parallel to the occlusal plane and there will be no need to make any bends in the archwire as was typical of the prior art devices.
A further development in orthodontic bracket design is depicted in U.S. Pat. No. 4,415,330. In this patent, the orthodontic bracket has a pair of tie wings having mesial and distal sides parallel to the tooth long axis which are used to facilitate alignment with the tooth long axis. The bracket also has an archwire slot and tie wing tips that are parallel to each other and parallel to the occlusal plane. Thus, this bracket provides both horizontal and vertical sight lines to facilitate in aligning the bracket on a tooth. Due to its specific configuration, this prior art bracket has an overall rhomboidal shape.
It has been determined that one of the primary reference lines used by the orthodontist in mounting a bracket on a patient's tooth is the occlusal edge of the base pad upon which the tie wings are mounted. The occlusal edge of the base pad is not only the longest edge of the orthodontic bracket, but it is the edge closest to the occlusal plane. Also, it has been found that a groove on the base pad bisecting the tie wings and being parallel to the tie wings, assist the orthodontist in aligning the bracket with the tooth long axis. It has been determined by orthodontists that the groove in the base pad and the inner edges of the tie wings provide the closest sight lines to the imaginary tooth long axis for assisting in aligning the bracket on the tooth. Some prior art brackets have incorporated a groove and a base pad with an occlusal edge parallel to the occlusal plane.
While the prior art brackets provide some assistance to the orthodontist, there remain problems in aligning a bracket due to the small size of the brackets and to fast-drying adhesives. Thus, what has been heretofore desired and unavailable is an orthodontic bracket having further sight lines that are parallel to the occlusal plane and to the tooth long axis which will assist the orthodontist in rapidly and more accurately mounting an orthodontic bracket on a tooth. The present invention provides these characteristics.